It derives from 4.4 BSD but it's more than that.

macOS includes a woefully outdated bash 3.2 due to GPL 3.0; they switched to zsh long ago.

I know. My question is, isn’t the reason the command line tools work the way they do simply that they’re essentially the BSD programs (give or take an Apple patch), with BSD options, not because they needed to work that way for Apple to get the OS certified?

Even if macOS wasn’t UNIX-certified, Apple would still be unwilling/unable to include the GNU software due to the license. I can’t see the Apple of today implementing a full suite of non-GNU software but with GNU-style options either.

So, POSIX compliant or not, there’s probably no world where `grep -P` works out of the box on a Mac.

	▲	p_ing 2 days ago \| parent [-]
		Sure, much like ping and tracert are BSD programs on Windows, just with a few different options that are OS-specific. There's no reason to include GNU anywhere. I don't know why Apple would.